初探LVS NAT、DR、keepalived
LB集群是load balance 集群的简写，翻译成中文就是负载均衡集群
LVS是一个实现负载均衡集群的开源软件项目
LVS架构从逻辑上可分为调度层(Director)、server集群层(Real server)和共享存储层
LVS可分为三种工作模式:
NAT(调度器将请求的目标ip即vip地址改为Real server的ip, 返回的数据包也经过调度器，调度器再把源地址修改为vip)
TUN(调度器将请求来的数据包封装加密通过ip隧道转发到后端的real server上，而real server会直接把数据返回给客户端，而不再经过调度器), DR(调度器将请求来的数据包的目标mac地址改为real server的mac地址，返回的时候也不经过调度器，直接返回给客户端)
LVS的调度算法：轮叫调度(Round Robin)(简称rr) ,加权轮叫(Weighted Round Robin)(简称wrr),最少链接(least connection)(LC),加权最少链接(Weighted Least Connections)(WLC) 等等
NAT模式:
三台机器：
A机：双网卡eth0:192.168.254.130 eth1:192.168.1.130（桥接，可看作公网ip）
B机：192.168.254.131
C机：192.168.254.133
A：dir B：rs1 c：rs2
A、B、C：需要装nginx
如果nginx没有在yum源上
wget www.lishiming.net/data/attachment/forum/epel-release-6-8_64.noarch.rpm
rpm -ivh epel-release-6-8_64.noarch.rpm
yum install -y nginx
A机操作：
[root@dir ~]#yum install -y ipvsadm
[root@dir ~]#vim /usr/local/sbin/lvs_nat.sh
#!/bin/bash
#director服务器开启路由转发功能
echo 1 > /proc/sys/net/ipv4/ip_forward
#关闭icmp的重定向echo 0 > /proc/sys/net/ipv4/conf/all/send_redirects
echo 0 > /proc/sys/net/ipv4/conf/default/send_redirects
echo 0 > /proc/sys/net/ipv4/conf/eth0/send_redirects
echo 0 > /proc/sys/net/ipv4/conf/eth1/send_redirects
#director设置NAT防火墙iptables -t nat -Fiptables -t nat -X
iptables -t nat -A POSTROUTING -s 192.168.254.0/24 -j MASQUERADE
#director设置ipvsadm
ipvsadm='/sbin/ipvsadm'
$ipvsadm -C
$ipvsadm -A -t 192.168.1.130:80 -s rr
$ipvsadm -a -t 192.168.1.130:80 -r 192.168.254.131:80 -m
$ipvsadm -a -t 192.168.1.130:80 -r 192.168.254.133:80 -m
[root@dir ~]# sh /usr/local/sbin/lvs_nat.sh
[root@dir ~]# ipvsadm -l
B、C机操作：
#修改gateway
vim /etc/sysconfig/network-scripts/ifcfg-eth0
网页端不太好测试，因为有缓存
DR模式：
A：192.168.122.129
B：192.168.122.140
C：192.168.122.141
A:
ipvsadm -C
iptables -t nat -F
ifdown eth1
vim /usr/local/sbin/lvs_dr.sh
#!/bin/bash
echo 1 > /proc/sys/net/ipv4/ip_forward
ipv=/sbin/ipvsadm
vip=192.168.122.139
rs1=192.168.122.140
rs2=192.168.122.141
ifconfig eth0:0 $vip broadcast $vip netmask 255.255.255.255 up
route add -host $vip dev eth0:0
$ipv -C
$ipv -A -t $vip:80 -s rr
$ipv -a -t $vip:80 -r $rs1:80 -g -w 1
$ipv -a -t $vip:80 -r $rs2:80 -g -w 1
sh /usr/local/sbin/lvs_nat.sh
ipvsadm -ln
B、C：
vim /usr/local/sbin/lvs_rs1.sh
#!/bin/bash
vip=192.168.122.139
ifconfig lo:0 $vip broadcast $vip netmask 255.255.255.255 up
route add -host $vip lo:0
echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
sh /usr/local/sbin/lvs_rs1.sh
测试：
需在新的机器上测试：
LVS结合keepalived:
A（dir） B(rs2) C(rs1)
在B上实现，如果C当掉,或者A当掉，B能够自动启动LVS DR，这里做的DR模式
A：
这里只留下eth0:192.168.122.129 这一个网卡
ipvsadm -C
yum install -y keepalived
vim /etc/keepalived/keepalived.conf
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.122.139
}
}
virtual_server 192.168.122.139 80 {
delay_loop 6
lb_algo rr
lb_kind DR
persistence_timeout 0
protocol TCP
real_server 192.168.122.140 80 {
weight 100
TCP_CHECK {
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 192.168.122.141 80 {
weight 100
TCP_CHECK {
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
复制配置文件之前需要在B上安装keepalived
scp /etc/keepalived/keepalived.conf 192.168.122.141:/etc/keepalived/keepalived.conf
/etc/init.d/keepalived start
ipvsadm -ln
ip addr
B：
yum install -y keepalived
vim /etc/keepalived/keepalived.conf
vrrp_instance VI_1 {
state BACKUP #这里需要更改为BACKUP
interface eth0
virtual_router_id 51
priority 99 #这里为99 或者90，比100小点
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.122.139
}
}
virtual_server 192.168.122.139 80 {
delay_loop 6
lb_algo rr
lb_kind DR
persistence_timeout 0
protocol TCP
real_server 192.168.122.140 80 {
weight 100
TCP_CHECK {
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 192.168.122.141 80 {
weight 100
TCP_CHECK {
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
/etc/init.d/keepalived start
yum install -y ipvsadm
ipvsadm -ln
ip addr
测试：
需要用其他虚拟机测试
都启动的情况：（3次rs1,1次rs2）
rs1当掉：（只有rs2）
dir当掉：（一次rs1，一次rs2）
